FR2807350A1 - Semiconductor process effluent removal unit maintains depressed pressure avoids blow back - Google Patents

Abstract

The semiconductor process effluent removal unit has a chamber (5) with air inlet (7) and liquid outlet (23) and internal transport pipe (9) with water jets (13) and effluent pipe (14).

Description

Device for discharging effluents from a semiconductor product processing installation The present invention relates to a device for discharging effluents from a semiconductor product processing installation.

The invention applies more particularly to factories for manufacturing microelectronic circuits from wafers of semiconductor material such as silicon.

The invention relates more particularly to devices for discharging essentially gaseous effluents which come out of engraving machines for cleaning wafers of semiconductor material.

This type of machine is usually fitted with a liquid effluent drain and an effluent outlet pipe in the form of gas and vapor; these effluents (referred to as gaseous below) essentially contain - in addition to air - water vapor, various acid products (such as HC1, HF, H2SO4), basic products (such as NH40H and / or products oxidants such as H202.

These products, although present in low concentration in the gaseous effluent are capable of reacting with each other to form in particular salts; these products are also liable to rapidly deteriorate the effluent discharge pipes to which such a machine is connected; in addition, it is necessary to avoid the return of these products inside the semiconductor product processing machine; for this purpose, the outlet outlet of the gaseous effluents of these machines is usually connected to a conduit (made of plastic material resistant to these products) which allows the transport of the gaseous effluent to a conduit of larger diameter which is connected at a first end to an extraction system, and at a second end to an ambient air intake in a neighboring room (gray); the effluents are evacuated by transport in these conduits under the effect of the vacuum caused by the extraction system.

These gaseous effluent discharge conduits must be constantly kept under vacuum with respect to the pressure prevailing in the machine and with respect to the pressure prevailing in the premises where these conduits extend; in fact, the air in the premises where these machines are installed specially filtered to avoid pollution of semiconductor materials by dust contained in the air; these premises are generally called "clean rooms".

In order to avoid the accumulation of solid particles in these conduits, in particular the salt deposits formed by reaction of the constituents of the gaseous effluents, the conduits are generally equipped with water spray nozzles intended to dilute and evacuate particles; the evacuation of water requires that the substantially horizontal duct portions be inclined at an angle sufficient to ensure the gravity flow of the water; the outlet orifice of such a machine generally connected to such an inclined section extending to the ceiling of the room receiving the machine, by a riser whose diameter is large enough to avoid the appearance of high pressure losses harmful to a good suction of gaseous effluents from the machine.

An object of the invention is to provide an improved system for discharging gaseous effluents from a machine for processing semiconductor materials.

An object of the invention is to propose an improved extraction system - called "bowl extraction" - acid and basic gaseous residues leaving such a machine.

According to one aspect, the invention consists in proposing a device for discharging gaseous effluents from a machine for processing semiconductor materials equipped with an effluent outlet pipe which comprises - a hollow body delimiting a chamber, a wall of said body comprising a first opening allowing air to enter the chamber, said body being provided with a second opening for connecting the chamber to an effluent discharge pipe, - an internal transport pipe of effluents extending inside the body and comprising a first and a second open end, - a sleeve or equivalent means for connecting one end of said internal conduit to said outlet conduit, - at least one nozzle or equivalent means for delivering water inside the internal effluent transport duct, said internal duct being arranged and shaped to ensure the flow of the water delivered by r the nozzle (s) up to its second end, said chamber and said first and second openings being arranged and shaped to allow said second end of the internal duct to be swept by the air admitted into the chamber through said first opening, so that the air mixed with the effluents (and if necessary with the water) is evacuated from the chamber by said second opening of the body.

The sweeping air flow from the portion of the chamber surrounding the internal effluent transport duct is generally kept continuous by connecting the device according to the invention to said exhaust duct forming part of a network of suction of effluents from several machines or sources of similar effluents.

The invention thus makes it possible to reduce the risk of effluent returning to machines during the various stages of their operation, in particular for machines provided with a door for introducing - into the machine - the semiconductor materials to be treated, the opening and closing of this door are liable to vary the (absolute) pressure prevailing in said outlet conduit fitted to the machine; the device according to the invention, thanks to the continuous sweeping of the second end, makes it possible to constantly maintain the latter in depression (relative to the pressure prevailing in the machine), and consequently allows a permanent entrainment of the effluents leaving the internal conduit transport by sadite second end, by the purge air flow.

In order to promote this training, the shape of the hollow body, the arrangement of said first and second openings provided in the walls thereof, are designed to cause, in the part of the chamber surrounding the internal transport duct, a current of air circulating along and around said internal transport duct (CIDT) in the direction of the second end sadite. Preferably, in effect, the portion of the hollow body surrounding the CIDT is elongated substantially along the latter, and said first opening of the body is arranged in the vicinity of said first end of said CIDT, and said second opening of the body is arranged in a wall extending beyond (and / or in extension) of said second end of said CIDT.

According to a preferred embodiment, said CIDT is essentially constituted by a first rectilinear section of tube of circular section made of PVDF, and the part of the hollow body surrounding the CIDT is essentially constituted by a second rectilinear section of tube of circular section made of PVDF of diameter and length respectively greater than the diameter and the length of the section of tube constituting the CIDT; the longitudinal axes of said first and second section of tube are substantially parallel or else inclined with respect to each other by an acute angle, the value of which is preferably situated in a range from 5 to 30 degrees.

The injection of water into the CIDT is preferably obtained by several rectilinear conduits extending radially - with reference to the longitudinal axis of the CIDT - through the chamber and the wall of the CIDT and the hollow body, and which are connected to a common deionized water supply pipe.

The invention provides a device which is simple to implement, inexpensive to manufacture and efficient.

Other characteristic advantages of the invention will be understood through the following description which refers to the accompanying drawings, which illustrate without any limiting character the preferred embodiments of the invention.

Figure 1 illustrates a longitudinal sectional view of a first embodiment of a device according to the invention.

FIG. 2 illustrates a view in longitudinal section of a second embodiment of a device according to the invention connected to an outlet duct of a treatment machine. Figure 3 is a sectional view along III-III of Figure 2 and illustrates the mounting of a device comprising two coaxial tube sections.

In operation (Figure 2), the device 1 is connected to a machine 2 for cleaning "wafers" provided with a conduit 3 effluent outlet extending along a horizontal axis 15; the hollow body 4 illustrated in FIG. 1 consists of a section of PVDF tube 18 with a horizontal axis 15, the left end of which is closed off by a disk-shaped bottom 24 pierced with a central orifice; this orifice allows the passage of effluents from the conduit 3 to the section 17 of PVDF tube with an axis 16 inclined at an angle 19 relative to the horizontal; for this purpose, a tubular sleeve 10 with an axis 15 is welded to the external face of the bottom 24, facing said central orifice and is fitted around the duct 3; in addition, the section of tube 17 forming the CIDT 9 is welded by its first end 11 to the internal face of the bottom 24, facing said central orifice in the extension of the sleeve 10.

The tube section 17 is also fixed inside the tube section 18 by support legs 22 extending radially - with reference to the axis 16 of the tube 17 -.

The intake of purge air into the cylindrical chamber 5 delimited by the body takes place through an opening 7 provided in the tubular wall 6 of the body, near the left end 11 of the tube 17; this flow is delivered by an air transport sheath 29 of axis 30.

The inclination of the axis 16 of the tube 17 causes the gravity flow, from left to right, of the water introduced into the tube 17 by nozzles 13 provided at the end of sections 20 of tube connected to a manifold 21 supply, until it leaves the tube 17 through its second end 12, in the chamber 5.

The gaseous effluents transported by the tube 17 are sucked in the air with which they mix and then escape from the chamber 5 through the opening 8 provided in the body 4; in the embodiment shown in Figure 2, the hollow body has a bend 25 extending the tube 18 and terminated by a flange 26 for connection to a conduit 14 for discharging effluents. A drain 23 for discharging the liquid phase out of the chamber 5 can be provided as illustrated in FIG. 1.

As illustrated in FIG. 2, conduit 29 and / or conduit 14 may extend through a well such as 28 provided in the floor 27 of the room receiving the machine 2.

Claims (1)

1. Device (1) for evacuating gaseous effluents from a machine (2) for processing semiconductor materials equipped with an effluent outlet conduit (3), characterized in that it comprises - a hollow body (4) delimiting a chamber (5), a wall (6) of said body comprising a first opening (7) allowing the entry of air into the chamber (5), said body being provided with a second opening ( 8) for the connection of the chamber to a pipe (14) for discharging effluents, - an internal pipe (9) for transporting effluents (CIDT) extending inside the body (4) and comprising a first and second end (11, 12) open, - a sleeve (10) or equivalent means for connecting one end (11) of said internal conduit (9) to said outlet conduit (3), at least one nozzle ( 13) or equivalent means for delivering water inside the internal effluent transport pipe (9), said internal pipe (9) being disposed and c shaped to ensure the flow of water delivered by the nozzle (s) to its second end, the chamber (5), and said first and second openings (7, 8) being arranged and shaped to allow sweeping said second end of the conduit (9) by the air admitted into the chamber through said first opening, so that the air mixed with the effluents is evacuated from the chamber through said second opening of the body. Device according to claim 1, in which the shape of the hollow body and the arrangement of said first and second openings provided in the walls thereof are designed to cause, in the part of the chamber surrounding the internal transport duct, a current of air circulating along and around said internal transport duct (CIDT) in the direction of the second end sadite. Device according to any one of claims 1 or 2, in which the portion of the hollow body surrounding the CIDT is elongated substantially along the latter, and said first opening of the body is arranged in the vicinity of said first end of said CIDT, and said second opening of the body is arranged in a wall extending beyond and / or in the extension of said second end of said CIDT. 4. Device according to any one of claims to 4, wherein said CIDT is essentially constituted by a first rectilinear section of tube (17) of circular section in PVDF, and the part of the hollow body surrounding the CIDT is essentially constituted by a second rectilinear section of tube (18) of circular section in PVDF of diameter and length respectively greater than the diameter than the length section of tube constituting the CIDT. 5. Device according to claim 4, wherein the longitudinal axes (15, 16) of said first and second tube sections are substantially parallel. 6. Device according to claim 4, in which the longitudinal axes (15, 16) of said first and second tube sections are inclined with respect to the other by an acute angle (19) whose value lies in the range from 5 to 30 degrees. 7. Device according to any one of claims to 6, in which the injection of water into the CIDT is obtained by several straight conduits (20) extending radially - with reference to the longitudinal axis of the CIDT - through of the chamber and of the wall of the CIDT and of the hollow body, and which are connected to a common conduit (21) for supplying deionized water. 8. Device according to any one of claims 1 to 7, which is connected to said conduit (14) for discharging effluents by passage through a floor (27).